Evolving interfaces

Is it possible to construct more usable interfaces that evolve over time? What are the conditions of natural selection? "Use" is an obvious criteria. How do you decide if something is more usable programatically? What are the markers that distinguish usability from popularity?

Interfaces naturally evolve over time anyway. They evolve based on feedback, usability testing, and fashionable trends to name just a few. Is it possible to preempt such trends by learning from user behaviour and having a web UI adapt automatically? How far do you take this? Sites that generate lots of traffic have plenty of data to train such an approach. Would there be any surprising results? Would it all just turn into a big jumbled mess?

I'm too lazy to look at the research, and I have *no idea* whatsoever about usability in general. People who actually know something about it - please reply in comments :) Ta muchly.